The occurrence of ovarian cancers in humans and experimental humors in rats can be correlated with several conditions which prevent normal cyclic functions, as well as conditions associated with elevated serum levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH). This project produces these conditions by parabiotically joining persistent estrus, androgenized female and gonadectomized male or female rats. The gonadotropic (FSH, LH and prolactin) and steroid (estrogen, androgen, and progestin) concentrations in their sera are measured by immunologic assays prior to, during and after ovarian tumors have developed. In addition the effect of cyclicity, induced by exogenous LH or hypothalamic releasing hormone, upon these hormones, the tumorigenic process, and the fully developed tumors, is being studied.